You have some immunity to the coronavirus if you’ve already had it, but how much and for how long are big unanswered questions. There’s evidence that reinfection is unlikely for at least three months even for people who had a mild case of COVID-19. Very few diseases leave people completely immune for life. Antibodies naturally wane over time, but they are only one piece of the body’s defenses. Other parts of the immune system can provide some protection too, and scientists are studying how they kick in with the coronavirus.